It is commonly known that a band brake assembly has been used to retard the rotational force of a rotatable drum with which a ground engaging wheel of a vehicle is connected. The band brake applies a frictional force to the outer surface of the drum. When applied, this frictional force acts to slow rotation of the wheel by counteracting a torque or rotational force conveyed to the drum by the vehicle transmission. Upon sufficient application of this frictional force, the drum and the wheel with which it is associated will slow or cease to rotate.
Band brakes, in general, have been used according to at least two designs for applications which include and extend beyond retarding motion of a wheel. Many of the designs have shared similar or common features. Among these features are the mounting of the band around the rotatable member whose motion it is to slow or stop. Specifically, the brake has ordinarily consisted of a clamp-like or C-shaped metal band that includes a lining of frictional material applied to an inner surface thereof and which is then placed against an outer surface of the rotatable member. The two designs, as mentioned above, locate the band relative to the member in this manner and can be described as being “single-acting” or “dual-acting”.
Single-acting and dual-acting band brakes differ from each other with respect to how the ends of the band are connected with the actuator used to tighten the band so as to determine how the band presses against the rotatable member. Single-acting brakes have included the stationary mounting of one end of the band to an anchor or part of the vehicle internal or external housing. The other end of the band has been movable and is often connected with an actuating member that, in turn, is associated with a hand or foot operated lever so as to allow the movable end to be moved as the actuator is moved. Connecting the band to a fixed support at one end while permitting the other end to be movable results in what has been known as a “cantilevered” support. This type of support can be described whereby one end of an element, such as the band, is free-standing and the other end is held stationary by connection with or mounting to a relatively immovable member.
Dual-acting brakes ordinarily include a mounting whereby an actuator of a particular description acts on both ends of the band to either push or pull the band together. With this pushing or pulling, the band becomes tightened and braking of the rotatable member occurs. Some of these dual-acting brakes have configurations which have both ends connected with an actuator.
The difference in the above descriptions or labelings is rooted in how the brake, as a whole, achieves its function of tightening the band around the drum so as to slow its rotation. The level of braking capacity, or force that is applied to the drum as a result of how the band is tightened against it, that may be delivered to the rotatable member has been dependent on the structural configuration of the brake and, particularly, the connection of the band to the actuator.
In each of the single and dual-acting brakes, the movable ends of the band have often been connected to their respective actuator at a single point or location. Upon movement of the actuator, the band ends are forced into motion which stresses the pins often used to connect the ends to the actuator. Stressing of the pins results from the pin or pins being mounted or connected with the actuator on a first end and not mounted thereto on a second end so as to provide a cantilevered post with which the band may be connected. Accordingly, the braking capacity available from either construction may be lost or greatly diminished since the pin or pins may become fatigued, leading to failure thereof, so as to not be able to adequately support the band.
In each of these designs, the mounting and actuating structure used to support and move the band, respectively, has often been placed outside of the rotatable member. Accordingly, the freedom to locate and size the band assembly and other structure necessary to operate the rotatable member, as in the case of wheel motor necessary to operate a wheel on a motorized vehicle, has been limited.
Thus, it would be beneficial to provide a band brake construction which possesses an ability to withstand the forces imposed upon it as braking occurs. Additionally, it would be beneficial to provide such a construction with an ability to fit within the wheel with which it is associated so as to permit flexibility in design and placement of components.